This invention relates to a printed circuit element comprising one or more metallic conductor layers and insulating layers fixedly joined to the conductor layers and a cover layer being arranged on the outer conductor layers or on the electrical components arranged thereon. Printed circuit elements are widely used inter alia in electronics, radio technology, computer technology, aircraft and aerospace, telecommunications and in electric motors. For purposes of electrical insulation, the printed electrical circuits are covered at least partially by an insulating cover layer.
The electrically insulating cover layer generally consists of an insulating lacquer applied to the circuit element. However, the insulating lacquers generally used leave the circuit elements to which the lacquers are applied with a number of disadvantages, namely:
(a) The insulating lacquers are not sufficiently heat-stable to withstand the extreme temperatures which can occur in the practical application of the printed circuit elements, without sustaining damage thereto. Thus, detrimental dimensional changes of the insulating properties can occur at high temperatures. PA1 (b) The lacquers are often mechanically unsatisfactory insofar as they are easily scratched and can flake off, again to the detriment of the electrical insulating effect. PA1 (c) The lacquers show unsatisfactory dielectric properties, often having inadequate electrical strength and the frequency behavior of the circuit elements to which the lacquers are applied can be impaired, for example through variations in the dielectric constant.